The results of the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study were published recently. This study of a California birth cohort investigated the relationship between exposure to flame retardant chemical pollutants in pregnancy and childhood, and subsequent neurobehavioral development. Why California? Because California children's exposures to these endocrine disruptors and neurotoxins are among the highest in the world.

What did they find? The researchers concluded that both prenatal and childhood exposures to these chemicals "were associated with poorer attention, fine motor coordination, and cognition" (particularly verbal comprehension) by the time the children reached school age. "This study, the largest to date, contributes to growing evidence suggesting that PBDEs [polybrominated diphenyl ethers, flame retardant chemicals] have adverse impacts on child neurobehavioral development." The effects may extend into adolescence, again affecting motor function as well as thyroid gland function. The effect on our thyroid glands may even extend into adulthood.

These chemicals get into moms, then into the amniotic fluid, and then into the breast milk. The more that's in the milk, the worse the infants' mental development may be. Breast milk is still best, but how did these women get exposed in the first place?

The question has been: Are we exposed mostly from diet or dust? Researchers in Boston collected breast milk samples from 46 first-time moms, vacuumed up samples of dust from their homes, and questioned them about their diets. The researchers found that both were likely to blame. Diet-wise, a number of animal products were implicated. This is consistent with what's been found worldwide. For example, in Europe, these flame retardant chemical pollutants are found mostly in meat, including fish, and other animal products. It's similar to what we see with dioxins--they are mostly found in fish and other fatty foods, with a plant-based diet offering the lowest exposure.

If that's the case, do vegetarians have lower levels of flame retardant chemical pollutants circulating in their bloodstreams? Yes. Vegetarians may have about 25% lower levels. Poultry appears to be the largest contributor of PBDEs. USDA researchers compared the levels in different meats, and the highest levels of these pollutants were found in chicken and turkey, with less in pork and even less in beef. California poultry had the highest, consistent with strict furniture flammability codes. But it's not like chickens are pecking at the sofa. Chickens and turkeys may be exposed indirectly through the application of sewer sludge to fields where feed crops are raised, contamination of water supplies, the use of flame-retarded materials in poultry housing, or the inadvertent incorporation of fire-retardant material into the birds' bedding or feed ingredients.

Fish have been shown to have the highest levels overall, but Americans don't eat a lot of fish so they don't contribute as much to the total body burden in the United States. Researchers have compared the level of PBDEs found in meat-eaters and vegetarians. The amount found in the bloodstream of vegetarians is noticeably lower, as you can see in my video Flame Retardant Pollutants and Child Development. Just to give you a sense of the contribution of chicken, higher than average poultry eaters have higher levels than omnivores as a whole, and lower than average poultry eaters have levels lower than omnivores.

What are the PBDE levels in vegans? We know the intake of many other classes of pollutants is almost exclusively from the ingestion of animal fats in the diet. What if we take them all out of the diet? It works for dioxins. Vegan dioxin levels appear markedly lower than the general population. What about for the flame retardant chemicals? Vegans have levels lower than vegetarians, with those who've been vegan around 20 years having even lower concentrations. This tendency for chemical levels to decline the longer one eats plant-based suggests that food of animal origin contributes substantially. But note that levels never get down to zero, so diet is not the only source.

The USDA researchers note that there are currently no regulatory limits on the amount of flame retardant chemical contamination in U.S. foods, "but reducing the levels of unnecessary, persistent, toxic compounds in our diet is certainly desirable."

The results of the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study were published recently. This study of a California birth cohort investigated the relationship between exposure to flame retardant chemical pollutants in pregnancy and childhood, and subsequent neurobehavioral development. Why California? Because California children's exposures to these endocrine disruptors and neurotoxins are among the highest in the world.

What did they find? The researchers concluded that both prenatal and childhood exposures to these chemicals "were associated with poorer attention, fine motor coordination, and cognition" (particularly verbal comprehension) by the time the children reached school age. "This study, the largest to date, contributes to growing evidence suggesting that PBDEs [polybrominated diphenyl ethers, flame retardant chemicals] have adverse impacts on child neurobehavioral development." The effects may extend into adolescence, again affecting motor function as well as thyroid gland function. The effect on our thyroid glands may even extend into adulthood.

These chemicals get into moms, then into the amniotic fluid, and then into the breast milk. The more that's in the milk, the worse the infants' mental development may be. Breast milk is still best, but how did these women get exposed in the first place?

The question has been: Are we exposed mostly from diet or dust? Researchers in Boston collected breast milk samples from 46 first-time moms, vacuumed up samples of dust from their homes, and questioned them about their diets. The researchers found that both were likely to blame. Diet-wise, a number of animal products were implicated. This is consistent with what's been found worldwide. For example, in Europe, these flame retardant chemical pollutants are found mostly in meat, including fish, and other animal products. It's similar to what we see with dioxins--they are mostly found in fish and other fatty foods, with a plant-based diet offering the lowest exposure.

If that's the case, do vegetarians have lower levels of flame retardant chemical pollutants circulating in their bloodstreams? Yes. Vegetarians may have about 25% lower levels. Poultry appears to be the largest contributor of PBDEs. USDA researchers compared the levels in different meats, and the highest levels of these pollutants were found in chicken and turkey, with less in pork and even less in beef. California poultry had the highest, consistent with strict furniture flammability codes. But it's not like chickens are pecking at the sofa. Chickens and turkeys may be exposed indirectly through the application of sewer sludge to fields where feed crops are raised, contamination of water supplies, the use of flame-retarded materials in poultry housing, or the inadvertent incorporation of fire-retardant material into the birds' bedding or feed ingredients.

Fish have been shown to have the highest levels overall, but Americans don't eat a lot of fish so they don't contribute as much to the total body burden in the United States. Researchers have compared the level of PBDEs found in meat-eaters and vegetarians. The amount found in the bloodstream of vegetarians is noticeably lower, as you can see in my video Flame Retardant Pollutants and Child Development. Just to give you a sense of the contribution of chicken, higher than average poultry eaters have higher levels than omnivores as a whole, and lower than average poultry eaters have levels lower than omnivores.

What are the PBDE levels in vegans? We know the intake of many other classes of pollutants is almost exclusively from the ingestion of animal fats in the diet. What if we take them all out of the diet? It works for dioxins. Vegan dioxin levels appear markedly lower than the general population. What about for the flame retardant chemicals? Vegans have levels lower than vegetarians, with those who've been vegan around 20 years having even lower concentrations. This tendency for chemical levels to decline the longer one eats plant-based suggests that food of animal origin contributes substantially. But note that levels never get down to zero, so diet is not the only source.

The USDA researchers note that there are currently no regulatory limits on the amount of flame retardant chemical contamination in U.S. foods, "but reducing the levels of unnecessary, persistent, toxic compounds in our diet is certainly desirable."

Natural immunomodulators that can help regulate our immune system without side-effects have been sought for centuries, and all the while they've been sitting in the produce aisle. Plants produce thousand of active compounds, many of which modulate our immune system, but we can't forget the fungi (see Boosting Immunity While Reducing Inflammation).

Mushrooms have used for centuries as folk remedies, and for good reason. Some have been shown to boost immune function, so much so that a type of fiber found in shiitake mushrooms is approved for use as adjunct chemotherapy, injected intravenously to help treat a variety of cancers by rallying our immune defenses.

More than 6,000 papers have been published on these so-called beta glucans, but almost all of the data about preventing infections had come from petri dish or lab animal studies, until a few years ago when a series of experiments on athletes showed beneficial effects in marathon runners (see Preserving Immune Function in Athletes With Nutritional Yeast). What about the rest of us? We didn't know... until now.

As I explore in my video, Nutritional Yeast to Prevent the Common Cold, beta glucan fiber found in baker's, brewer's and nutritional yeast helps to maintain our body's defense against pathogens even in nonathletes, according to a double-blind, randomized, placebo-controlled trial. The recurrence of infections with the common cold was reduced by 25% in those that ate the equivalent of about a spoonful of nutritional yeast a day, and had fewer cold-related sleeping difficulties when they did get sick.

What about half a spoonful a day? Still worked! Subjects experienced a big drop in common cold incidence and a reduction in symptoms as well. Why is this? This study found that not only were upper respiratory infection symptoms diminished, but that mood states appeared to improve, for example a significant boost in feelings of "vigor." So the researchers suggest that maybe the yeast fiber is able to counteract the negative effects of stress on the immune system.

In terms of side-effects, two folks reported stomachaches, but they were both in the placebo group.

Unlike antibiotics and antivirals, which are designed to kill the pathogen directly, these yeast compounds instead appear to work by stimulating our immune defenses, and as such don't share the same antibiotic side effects. They stimulate our immune defenses presumably because our body recognizes them as foreign. But if it's treated like an invader, might it trigger an inflammatory response? Turns out these fiber compounds may actually have an anti-inflammatory effect, suggesting nutritional yeast may offer the best of both worlds, boosting the infection fighting side of the immune system while suppressing inflammatory components.

Yeast is high in purines, so those with gout, uric acid kidney stones, and new organ transplant recipients may want to keep their intake to less than a teaspoon a day. But is there any downside for everyone else? In California some packages of nutritional yeast are slapped with prop 65 warning stickers, suggesting there's something in it exceeding cancer or birth defect safety limits. I called around to the companies and it turns out the problem is lead. California state law says a product cannot contain more than half of a microgram of lead per daily serving, so I contacted the six brands I knew about and asked them how much lead was in their products.

KAL originally said "<5 ppm," but when we called back they said "<3 ppm." Even if it's 3, that translates into less than 45 micrograms per serving, nearly a 100 times more than the California limit. But perhaps that's better than Bob's Red Mill or Frontier Coop, who evidently don't test at all. But at least they got back to me. Redstar brand failed to respond to multiple attempts to contact them. Now Foods said they test for lead and claim that at least their recent batches meet the less than a half a microgram California standard. Unfortunately, despite repeated requests they would not provide me with documentation to substantiate their numbers. My favorite response was from Bragg's who sent me the analysis certificate from the lab showing less than 0.01 ppm, which means at most less than half the California standard, which I believe is the most stringent in the world. To put the numbers in context, in determining how much lead manufacturers can put into candy likely to be frequently consumed by small children, the Food and Drug Administration would allow about 2 micrograms a day in the form of lollipops, but as far as I'm concerned the less lead the better.

I was so frustrated by the lack of transparency I decided to test them for lead myself. NutritionFacts.org hired an independent lab to conduct our own tests for lead and shipped out 8 samples of nutritional yeast in their original package. The lab used standard practices for lead testing known as Official Methods of Analysis set by AOAC International. Lab technicians determined the lead values based on California Prop 65 standards. Here are the results from the brands we tested:

Whole Foods - Test report shows lead levels at 0.012 ppm. It would take six tablespoons a day to exceed the MADL.*

So what do all those numbers mean? None of the brands tested exceeded California prop 65 standards. No matter what brand, consuming a typical serving (2 tablespoons) per day is still well within safe limits.

* The Maximum Allowable Dose Level for lead as a developmental toxin is 0.5 micrograms a day. How are MADL's calculated? Basically scientists figure out what the "no observable effect level" is, the level at which no birth defects or reproductive toxicity can be found, and then introduce a 1000-fold safety buffer. So for example, let's say there's some chemical that causes birth defects if expectant moms are exposed to two drops of the chemical a day, but there's no evidence that one drop a day is harmful. Do they set the Maximum Allowable Dose Level at one drop? No, they set it at 1/1000th of a drop to account for scientific uncertainty and to err on the side of caution. So by saying six tablespoons a day of nutritional yeast may exceed the MADL is in effect saying that the level of lead found in 6,000 tablespoons of nutritional yeast may cause birth defects. Like mercury, though, as far as I'm concerned the less lead exposure the better. I hope this will inspire companies to do further testing to see if the levels we found were just flukes.

Natural immunomodulators that can help regulate our immune system without side-effects have been sought for centuries, and all the while they've been sitting in the produce aisle. Plants produce thousand of active compounds, many of which modulate our immune system, but we can't forget the fungi (see Boosting Immunity While Reducing Inflammation).

Mushrooms have used for centuries as folk remedies, and for good reason. Some have been shown to boost immune function, so much so that a type of fiber found in shiitake mushrooms is approved for use as adjunct chemotherapy, injected intravenously to help treat a variety of cancers by rallying our immune defenses.

More than 6,000 papers have been published on these so-called beta glucans, but almost all of the data about preventing infections had come from petri dish or lab animal studies, until a few years ago when a series of experiments on athletes showed beneficial effects in marathon runners (see Preserving Immune Function in Athletes With Nutritional Yeast). What about the rest of us? We didn't know... until now.

As I explore in my video, Nutritional Yeast to Prevent the Common Cold, beta glucan fiber found in baker's, brewer's and nutritional yeast helps to maintain our body's defense against pathogens even in nonathletes, according to a double-blind, randomized, placebo-controlled trial. The recurrence of infections with the common cold was reduced by 25% in those that ate the equivalent of about a spoonful of nutritional yeast a day, and had fewer cold-related sleeping difficulties when they did get sick.

What about half a spoonful a day? Still worked! Subjects experienced a big drop in common cold incidence and a reduction in symptoms as well. Why is this? This study found that not only were upper respiratory infection symptoms diminished, but that mood states appeared to improve, for example a significant boost in feelings of "vigor." So the researchers suggest that maybe the yeast fiber is able to counteract the negative effects of stress on the immune system.

In terms of side-effects, two folks reported stomachaches, but they were both in the placebo group.

Unlike antibiotics and antivirals, which are designed to kill the pathogen directly, these yeast compounds instead appear to work by stimulating our immune defenses, and as such don't share the same antibiotic side effects. They stimulate our immune defenses presumably because our body recognizes them as foreign. But if it's treated like an invader, might it trigger an inflammatory response? Turns out these fiber compounds may actually have an anti-inflammatory effect, suggesting nutritional yeast may offer the best of both worlds, boosting the infection fighting side of the immune system while suppressing inflammatory components.

Yeast is high in purines, so those with gout, uric acid kidney stones, and new organ transplant recipients may want to keep their intake to less than a teaspoon a day. But is there any downside for everyone else? In California some packages of nutritional yeast are slapped with prop 65 warning stickers, suggesting there's something in it exceeding cancer or birth defect safety limits. I called around to the companies and it turns out the problem is lead. California state law says a product cannot contain more than half of a microgram of lead per daily serving, so I contacted the six brands I knew about and asked them how much lead was in their products.

KAL originally said "<5 ppm," but when we called back they said "<3 ppm." Even if it's 3, that translates into less than 45 micrograms per serving, nearly a 100 times more than the California limit. But perhaps that's better than Bob's Red Mill or Frontier Coop, who evidently don't test at all. But at least they got back to me. Redstar brand failed to respond to multiple attempts to contact them. Now Foods said they test for lead and claim that at least their recent batches meet the less than a half a microgram California standard. Unfortunately, despite repeated requests they would not provide me with documentation to substantiate their numbers. My favorite response was from Bragg's who sent me the analysis certificate from the lab showing less than 0.01 ppm, which means at most less than half the California standard, which I believe is the most stringent in the world. To put the numbers in context, in determining how much lead manufacturers can put into candy likely to be frequently consumed by small children, the Food and Drug Administration would allow about 2 micrograms a day in the form of lollipops, but as far as I'm concerned the less lead the better.

I was so frustrated by the lack of transparency I decided to test them for lead myself. NutritionFacts.org hired an independent lab to conduct our own tests for lead and shipped out 8 samples of nutritional yeast in their original package. The lab used standard practices for lead testing known as Official Methods of Analysis set by AOAC International. Lab technicians determined the lead values based on California Prop 65 standards. Here are the results from the brands we tested:

Whole Foods - Test report shows lead levels at 0.012 ppm. It would take six tablespoons a day to exceed the MADL.*

So what do all those numbers mean? None of the brands tested exceeded California prop 65 standards. No matter what brand, consuming a typical serving (2 tablespoons) per day is still well within safe limits.

* The Maximum Allowable Dose Level for lead as a developmental toxin is 0.5 micrograms a day. How are MADL's calculated? Basically scientists figure out what the "no observable effect level" is, the level at which no birth defects or reproductive toxicity can be found, and then introduce a 1000-fold safety buffer. So for example, let's say there's some chemical that causes birth defects if expectant moms are exposed to two drops of the chemical a day, but there's no evidence that one drop a day is harmful. Do they set the Maximum Allowable Dose Level at one drop? No, they set it at 1/1000th of a drop to account for scientific uncertainty and to err on the side of caution. So by saying six tablespoons a day of nutritional yeast may exceed the MADL is in effect saying that the level of lead found in 6,000 tablespoons of nutritional yeast may cause birth defects. Like mercury, though, as far as I'm concerned the less lead exposure the better. I hope this will inspire companies to do further testing to see if the levels we found were just flukes.

Every year I scour the world's scholarly literature on clinical nutrition, pulling together what I find to be the most interesting, practical, and groundbreaking science on how to best feed ourselves and our families. I start with the thousands of papers published annually on nutrition (27,000 this year--a new record!) and, thanks to a crack team of volunteers (and now staff!), I'm able to whittle those down (to a mere 8,000 this year). They are then downloaded, categorized, read, analyzed, and churned into the few hundred short videos. This allows me to post new videos and articles every day, year-round, to NutritionFacts.org. This certainly makes the site unique. There's no other science-based source for free daily updates on the latest discoveries in nutrition. The problem is that the amount of information can be overwhelming.

Currently I have more than a thousand videos covering 1,931 nutrition topics. Where do you even begin? Many have expressed their appreciation for the breadth of material, but asked that I try to distill it into a coherent summary of how best to use diet to prevent and treat chronic disease. I took this feedback to heart and in 2012 developed Uprooting the Leading Causes of Death, which explored the role diet may play in preventing, arresting, and even reversing our top 15 killers. Not only did it rise to become one of the Top 10 Most Popular Videos of 2012, it remains my single most viewed video to date, watched over a million times (NutritionFacts.org is now up to more than 1.5 million hits a month!).

Every year I wonder how I'm going to top the year before. Knowing how popular these live presentations can be and hearing all the stories from folks about what a powerful impact they can have on people's lives, I put my all into this new 2015 one. I spent more time putting together this presentation than any other in my life. It took me an entire month, and when you see it I think you'll appreciate why.

This year, I'm honored to bring you Food as Medicine, in which I go through our most dreaded diseases--but that's not even the best part! I'm really proud of what I put together for the ending. I spend the last 20 minutes or so (starting at 56:22) going through a thought experiment that I'm hoping everyone will find compelling. I think it may be my best presentation ever. You be the judge.

You can watch it at no cost online, but it is also available on DVD through my website or on Amazon. If you want to share copies with others, I have a five for $40 special (enter coupon code 5FOR40FAM). All proceeds from the sales of all my books, DVDs, downloads, and presentations go to the 501c3 nonprofit charity that keeps NutritionFacts.org free for all, for all time. If you want to support this initiative to educate millions about eradicating dietary diseases, please consider making a donation.

In a study highlighted in my video, California Childen Are Contaminated, researchers analyzed the diets of California children ages two through seven to determine the cancer and non-cancer health effects from food contaminant exposures. It turns out food may be the primary route of exposure to toxic heavy metals, persistent pollutants, and pesticides. "Though food-borne toxic contaminants are a concern for all ages, they are of greatest concern for children, who are disproportionately impacted because they're still developing and have greater intake of food and fluids relative to their weight. Pediatric problems that have been linked to preventable environmental toxin exposures include cancer, asthma, lead poisoning, neurobehavioral disorders, learning and developmental disabilities, and birth defects."

The good news is that changing one's diet can change one's exposure. Quoting from the study, "A diet high in fish and animal products, for example, results in greater exposure to persistent pollutants like DDT and dioxins and heavy metals than does a plant-based diet because these compounds bioaccumulate up the food chain." Plants are at the bottom of the food chain. The sample of California kids, however, was not eating a plant-based diet. Cancer benchmark levels were exceeded by all 364 children for arsenic, the banned pesticide dieldrin, a metabolite of DDT called DDE, and dioxins.

Children exceeded safety levels by a greater margin than adults. This is especially of concern for children because all of these compounds are suspected endocrine disruptors and thus may impact normal development. Cancer risk ratios were exceeded by over a factor of 100 for both arsenic and dioxins.

Which foods were the worse? For preschoolers, the number one food source of arsenic was poultry, though for their parents, it was tuna. The number one source of lead was dairy, and for mercury it was seafood. And the number one source of the banned pesticides and dioxins was dairy. (See Preventing Parkinson's Disease With Diet.)

The researchers also recommended children should eat lower quantities of chips, cereal, crackers, and other crispy carbs to reduce acrylamide intake.

The California study didn't split up the groups by gender, but a similar study in Europe found that men had higher levels of some of these pollutants than women. For example, levels of the banned pesticide chlordane were higher in men, but women who never breastfed were right up there alongside men, with the lowest levels found in women who breastfed over 12 months. Therefore, it is likely that the lactation-related reduction in blood pollutant levels partly explains the lower body burdens among women compared with men. So cows can lower their levels by giving some to us, then we can pass it along to our children.

What non-cancer effects might some of these pollutants have? They can affect our immune system. Studies clearly demonstrate the "ability of dioxins and related compounds to have a long-lasting and deleterious impact on immune function." This manifests as increased incidences of respiratory infections, ear infections, cough, and sore throat. At first, most of the data was for during infancy, but now we have follow-up studies showing that the immunosuppressive effects of these toxins may persist into early childhood, so we should try to reduce our exposure as much as possible. Because these pollutants accumulate in animal fat, consuming a plant-based diet-decreasing meat, dairy, and fish consumption-may reduce exposure for children and adults alike.

Many studies have shown that calorie restriction, without malnutrition, can increase lifespan and lower the risk of age-related diseases, such as cancer.

However, for many people, calorie restriction clearly has its drawbacks. In the classic Minnesota Starvation Study, many of the volunteers suffered a preoccupation with food, constant hunger, binge eating, and lots of emotional and psychological issues. Even researchers who study caloric restriction rarely practice it. There's got to be a better way to suppress the aging engine enzyme, TOR (see Why Do We Age?for more on TOR).

That's why researchers were so excited about rapamycin, a drug that inhibits TOR, thinking it could be caloric restriction in a pill. But like any drug, it a long list of potentially serious side effects. There's got to be a better way.

The breakthrough came when scientists discovered that the benefits of dietary restriction may be coming not from restricting calories, but from restricting protein intake (See my video Caloric Restriction vs. Animal Protein Restriction). If we look at the first comprehensive, comparative meta-analysis of dietary restriction, "the proportion of protein intake was more important for life extension than the degree of caloric restriction." In fact, just "reducing protein without any changes in calorie level have been shown to have similar effects as caloric restriction."

That's good news. Protein restriction is much less difficult to maintain than dietary restriction, and it may even be more powerful because it suppresses both TOR and IGF-1, the two pathways thought responsible for the dramatic longevity and health benefits of caloric restriction.

Some proteins are worse than others. One amino acid in particular, leucine, appears to exert the greatest effect on TOR. In fact, just cutting down on leucine may be nearly as effective as cutting down on all protein. Where is leucine found? Predominantly animal foods: eggs, dairy, and meat (including chicken and fish). Plant foods, such as fruits, vegetables, grains, and beans, have much less.

"In general, lower leucine levels are only reached by restriction of animal proteins." To reach the leucine intake provided by dairy or meat, we'd have to eat nine pounds of cabbage--about four big heads--or 100 apples. These calculations exemplify the extreme differences in leucine amounts provided by a conventional diet in comparison to a plant-based diet. The functional role of leucine in regulating TOR activity may help explain the extraordinary results reported in the Cornell-Oxford-China Study, "since quasi-vegan diets of modest protein content tend to be relatively low in leucine."

This may also help explain the longevity of populations like the Okinawa Japanese, who have about half our mortality rate. The traditional Okinawan diet is only about 10% protein, and practically no cholesterol, because they ate almost exclusively plants. Less than one percent of their diet was fish, meat, eggs, and dairy - the equivalent of one serving of meat a month and one egg every two months. Their longevity is surpassed only by vegetarian Adventists in California, who have perhaps the highest life expectancy of any formally studied population in history.

Used as a coloring agent in products ranging from colas and beer to gravies and soy sauce, caramel coloring may be the world's most widely consumed food coloring. It helps grocery stores sell more than a billion servings of food and beverages a day. Unfortunately, the manufacturing of certain artificial caramel colorings can lead to the formation of carcinogens such as 4-methylimidazole, which causes cancer in mice but not rats (or at least, not male rats). However, it is unclear whether humans are more like mice or rats in terms of their response to the carcinogen.

To be safe, California officially listed it as a carcinogen and started requiring warning labels on soft drinks containing more than 29 micrograms per serving. The soft drink industry was unsuccessful in opposing the action, so they were forced to reduce carcinogen levels in their products--but only in California. Buy Coke anywhere else, and it may have up to five times the limit (See Is Caramel Color Carcinogenic?).

As traditional East Asian diets have westernized, breast cancer rates have risen. Some researchers have linked this to a quadrupling of animal product consumption. In my video Which Seaweed Is Most Protective Against Breast Cancer, you can see the breast cancer rate of Japanese women living in Japan. Within 10 years of immigrating to the United States, their risk increases, and if they hang around long enough, their risk goes up even more, although it is still somewhat lower than the U.S. national average. This may be because of some of the dietary habits they carry with them—soy and green tea consumption, perhaps eating more mushrooms and seaweed.

We’ve known for over a decade that in vitro (in a Petri dish) seaweed broth is effective at clearing cancer cells. In the video, you can see three different types of human breast cancer exposed to either a widely used chemotherapy drug or a sea vegetable. The seaweed worked better. And unlike the chemo, it didn’t hurt normal, non-cancerous breast cells. What about outside of the test tube, in people?

Well, a population study comparing women with breast cancer to women without found that consuming a single sheet of nori a day may cut a woman’s odds of breast cancer in half. We think it’s because seaweed favorably alters estrogen metabolism, likely due to modulating women’s gut bacteria. The more seaweed we eat, the less estrogen we have in our system, which may lower breast cancer risk.

The breast cancer protection may be because of all the fiber in sea vegetables, or because seaweed may block the enzyme that undermines our body’s attempt to flush out excess hormones. Or seaweed may somehow interfere with estrogen binding to estrogen receptors. Whatever the cause, to effectively lower their estrogen levels, Asian women may be able to get away with about one sheet of nori a day, but American women are physically so much larger that it may take closer to two. There are lots of yummy seaweed snacks out there to make it a tasty experience—just try to get some low-fat, low-sodium ones. They’re just like kale chips, munchies made out of dark green leafy vegetables—can’t beat that!

The seaweed used fresh in seaweed salads, wakame, unfortunately did not appear to reduce breast cancer risk. Wakame consumption has, however, been found to lower blood pressure in hypertensives (people with high blood pressure). Just two teaspoons of seaweed salad a day for a month dropped people’s blood pressure 14 points, and two months of wakame was associated with up to a two inch skinnier waistline.

As I’ve mentioned before, I’d recommend avoiding hijike, which tends to have too much arsenic (see Avoiding Iodine Deficiency), and kelp, which tends to have too much iodine (see Too Much Iodine Can Be as Bad as Too Little). In fact, too much seaweed of any type may actually increase our risk for thyroid cancer because of the amount of iodine we’d be taking in, but there does not appear to be any increased risk at the levels of consumption I’m talking about, like a sheet of nori every day. And a study of seaweed eaters in California actually found decreased risk, but, again, we’re talking a modest level of intake.

I’ve frequently talked about the benefits of dietary diversity, eating different families of fruits and vegetables, eating different parts of individual plants—such as beets and beet greens. If we just stick to land plants, though, we’re missing out on all the plants from the other 70% of planet earth. Sea vegetables have phytonutrients found nowhere else, special types of fiber, and unique carotenoids and polysaccharides, and various polyphenol defense compounds, each of which may have anti-cancer properties. I encourage everyone to try experimenting until you find a sea vegetable you like, even if that means just sprinkling some powdered dulse on your food. More on the importance of dietary diversity in Garden Variety Anti-Inflammation, Apples and Oranges: Dietary Diversity, and Constructing a Cognitive Portfolio.